A) As I understand from upload script, using sleep 1 caused an issue as reported by me here https://forum.arduino.cc/index.php?topic=369653.0 Will the SLEEP be right approach, when we deal with multiple processor speeds, some may take more time and some less time, is there a way to find processor speed and delay the script, than using SLEEP. I just changed SLEEP to 3 seconds, then I could upload to CURIE
B) From verbose output, I could see "Invalid DFU signature and it is not supported in next release" Is it concern or this warning can be ignored for now.
C) "Forcing 1200 baudrate to reset in DFU mode" seems to be failing for many users,as I read in forums. Temporary solution is to use Master reset.. Can someone guide me which script is invoked to do this resetting to DFU mode. Looks like there is a bug.